Compound incandescent electric lamp.



No. 706,3l4. 7 Patented Aug, 5, I902. H. GILMDRE.

COMPOUND INCANDESGENT ELECTRIC LAMP.

(Application filed Feb. 7, 1901. 4

(No Mudei.) 2 Sheets-Sheet l.

No. 706,3l4. Patented Aug. 5, I902.

H. GILMORE.

COMPOUND INBANDESCENT ELECTRIC LAMP.

(Application filed Feb. 7, 1801.) (No Model.)

2 Sheets-Sheet 2.

litres fi rarns ATENT OFFICE.

IIOIVARD GILMORE, OF BOSTON, MASSACHUSETTS.

COMPOUND INCANDESCENT ELECTRIC LAMP.

SPECIFICATION forming part of Letters Patent No. 706,314, dated August5, 1902.

Application filed February 7,1901. Serial No. 46.413. (No model.

To all whom, it may concern.-

Be it known that I, HOWARD GILMORE, of Boston, in the county of Suffolkand State of Massachusetts, have invented a new and useful CompoundIncandescent Electric Lamp, of which the following is a specification,reference being had to the accompanying drawings, in which- Figure 1 isa diagram showing all the necessary electrical connections and also aswitch for short-circuiting or cutting out the lowcandle-power lamp.Fig. 2 is a sectional elevation of the proposed form of my lamp. Fig. 3is a modified form in which the low-candlepower lamp has a base andsocket attached to it; but the base is fitted in aseparate socket,which'is also provided with a base. Fig. 4 is also a modificationshowing a base with two sockets, one for the low-candle-power lamp, theother for the high-candle-power lamp.

The object of my invention is to provide a compound lamp or two bulbs,each with its own filament so combined that the filaulents of both lampsare in series when only the lamp of small candle-power is lighted andthe filament of thelamp of low candle-power is shunted or wholly cut out(it is practically immaterial which) when the lamp of higher candlepoweris lighted; and my invention is a compoundlampconsistin g of twolamps,one of low candle-power,the other of higher candle-power, thefilament of the low-candle-power lamp be? ing of much smaller diameterthan that of the high-candle-power lamp, and means for connecting thehigh and low candle-power lamps in series and for disconnecting thelow-candle-power lamp at will, so that when both lamps are connected inseries only the lamp of low candle-power will come to full glow, butwhen the low-candle-power lamp is shunted or cut out only the lamp ofhigh candlepower will come to full glow. In the best form of myinvention each lamp has its own base and socket, and there is a thirdbase and socket, which is common to both lamps, and this combination oftwo lamps with three bases and three sockets is of practical importancein the practical manufacture of my compound lamp, for although thetwolamps may be one structure or may be wholly independent except as towiring, yet to make my compound lamp in its commercial form it ispractically necessarynot only that each lamp shall have its own socketand base, but also that these two sockets and two bases shall have athird base connecting both lamps with the main wires. By thiscombination the two lamps are connected together so that either can beremoved and replaced and both can be attached to and detached from themain lines at pleasure and without disconnecting either from the other.

In Fig. 1, a and a indicate suitable electhe main circuit. The conductora from electrode a is connected to metal shell (1, which is fast to thelow-candle-power lamp A. The filament b of lamp B is connected at oneend to metal shell I) and at its other end to the insulated electrodes bWhen the key K is in the position shown in Fig. l, the circuit isestablished through conductor a shells a and I), (which are connected bystrip b filament b of lamp B, electrode b contacts and 18, (which arethen in contact,) conductor a to electrode a, and filament b of lamp Bis then in full glow, precisely as if the lowcandle-power lamp A werenot present; but when key K separates contacts 7t and k the circuit isestablished through conductor a filament b of lamp B, electrode 19 screw76, filament a of lamp A, contact 70 conductor co to electrode a, andfilaments b and aiare then in series, but filament 1) requires a certaincurrent to bring it to full glow and filament a requires a much smallercurrent to bring it to full glow, and the current is reduced by bringingfilament a in series with filament b to an amperage which causesfilament a to glow, but which is insufficient to make filament b glowappreciably. In short, when both lamps A and B are in series lamp Aaloneis brought tofull glow and lamp B is dark or at most at a dull red; butwhen lamp A is disconnected lamp B of course is at full glow, for thenlamp A is practically not pres ent.

In Fig. 2 I show the preferred form of my compound lamp, in which formlamp A is provided with two bases (1 and, (P, on e,cZ, to fit the usualsocket (not shown in Fig. 2) whose electrodes are terminals of the maincircuit, and the other, d to fit the special socket d which is connectedelectrically to socket d trodes,\vhichare connected,respectively,with

for base d of lamp B. This form shows lamp A with a base and a separatesocketthat is, in Fig. 2 lamp A has two bases 61 (1 made as one piecewith it, and two sockets 01 d connected as one piece.

In Fig. 3 lamp Ais made as one piece with base (1 and socket 61 socket dand base d being made as one piece. In Fig. l lamp A is made with basecl the two sockets cl (Z being made as one piece with base d Thisissimply in order that both lamps A and B may be readily detached andeither or both be replaced, for in practice lamp A will usually be ofmuch longer life than lamp B, and while the two sockets made as onepiece (shown in Fig. 2) connecting lamps A and B are much better thanthe two sockets made as one piece with a base, (shown in Fig. 4,) mainlybecause this construction obstructs the light from lamp A, yet it isimmaterial whether lamp A be made as in one piece with two bases or twosockets or one base and one socket, for each base must fit its socket,and

it is only a question whether the external part called a socketor theinternal part called a base shall be madeas in one piece with lamp A,while this feature of my invention is the combination of two lamps by abase and socket for each lamp and a third base and socket connectingboth lamps with the main circuitthat is, two lamps connected together bytwo bases and two sockets and connected as a whole to the main circuitby a third base and socket and provided with a switch which in oneposition causes the current to flow through both lamps in series and thelow-candle-power lamp alone to burn, the high-candle-power lamp thusserving as a rheostat, but when in the other position disconnects orshunts thelow-candle-powerlamp and causes the high-candle-power lamp toburn.

Lamp A has one set of three contacts and a second set of two contacts,and two of the three contacts are connected with the filament, andone ofthese two contacts connected with the filament is also connected to oneof the set of two contacts. The third contact of the set of three isconnected to the other contact of the set of twothat is, in Fig. 1 theset of three contacts are It, and b and the set of two contacts are aand a. The two contacts 7t and 70 are connected, respectively, toterminals of filament a and the contact 70 is also connected to thecontact a of the set of two. The third contact I) of the set of three isconnected to the contact a of the set of twothat is, contacts Z), a, anda are connected by strip 6 and contacts k and a are connected by wire (1This is an important feature of my invention, for in practice I putlamps A on the market in the form shown in Figs. 2 and 3, which aresubstantially the same, the sole difference being that'in Fig. 2 lamp Ais made with the sets of terminals in the form of bases (1 01 while inFig. 3 the sets of terminals are made one set in the form of a base d,the other set in the form of a socket (1 In Fig. 2 the set of threecontacts are 70, I0 and the shell b, forming part of base d and the setof two contacts are a and a, while in Fig. 3 the set ofthree contactsare 70, 70 and the shell I), and the set of two contacts are theinsulated electrode 11 and the shell-making socket (Z which shell isconnected with shell I) by strip 71 What I claim as my invention is 1.In combination two incandescent lamps one with a fine filament the otherwith a coarser filament and means for passing the current through thelamp with the coarser filament to bring that lamp alone to full glow,and means for passing the current through both lamps in series and soreduce the amperage that only the lamp with the fine filament Will bebrought to full glow.

2. An incandescent electric lamp comprising a bulb, a filament in thatbulb, one set of contacts comprising three contact-pieces and anotherset of contacts comprising two contact-pieces, with twov contact-piecesof the three-piece set connected respectively to the terminals of thefilament and one of those two contact-pieces connected also to onecontact of the two-piece set; having one contact of the three-piece setand one contact of the twopiece setto be connected respectively with themain wires.

HOWARD GILMORE.

